Support Layers Incorporating Cellulose Nanofibers for Thin Film Composite Membranes for Pressure Retarded Osmosis

摘要

Pressure retarded osmosis (PRO) is a potential technology for renewable energy production using salinity gradients and low-grade or waste heat. Recent research has shown that higher power densities, and therefore power production, can be generated using highly concentrated draw solutions. These highly concentrated solutions, however, require high pressure to reach maximum power density. Due to the osmotic driving force found in both PRO and forward osmosis (FO), thin film composite (TFC) FO membranes have been chosen as model membranes for pressure retarded osmosis. These membranes, however, fail under even modest pressures without significant support. In addition, the highly hydrophobic support layers of typical TFC membranes exacerbate the problems of internal concentration polarization by limiting the wetted channels for water and salt transport within the support layers. Using the TFC forward osmosis membrane as a platform, we have developed a polysulfone composite with cellulose nanofibers as support layers to improve the mechanical stability of the membrane under high pressure.